In the prior art, the use of conveyors to transport cargo, bulk materials and the like are well known. One type of a conveyor system especially adapted for baggage such as that found in airports is an over-under belt conveyor system as disclosed in U.S. Pat. No. 5,363,951 to Mensch. This patent, incorporated in its entirety by reference herein, discloses a conveyor system which has upper and lower vertically spaced, oppositely moving load carrying runs, each having an entrance end and an exit end. The system is especially adapted for two-way conveyance of articles under varying load conditions in the handling of baggage at an airport.
Often times, a number of over-under conveyor systems or a plurality of single conveyors are arranged in tunnels in airports employing one or more intermediate terminals to accommodate increased baggage handling requirements. The over-under conveyor systems are more advantageous in terms of tunnel construction costs than a number of single conveyors since more conveyor runs can be fit into a given tunnel (the tunnel is not as wide as those using multiple single conveyors but has a slightly increased height).
With the need to further reduce construction costs, particularly for tunnel construction and the drawbacks of over-under conveyors (increased tunnel height), a need has developed to provide improved conveyor systems which offer equivalent baggage handling capability while reducing space requirements and tunnel construction costs.
The present invention solves this need by providing a side-by-side conveyor system which provides the same baggage carrying capacity as an over-under conveyor system in less space, thereby reducing tunnel construction costs. The present invention uses twisting roll assemblies to link an endless belt between oppositely moving baggage travel paths of carry and return conveyors while still maintaining the baggage carrying surface of the endless belt in the correct orientation.
The use of roll assemblies to rotate or twist endless belts has been proposed in the bulk material handling arts. U.S. Pat. Nos. 2,784,834 and 2,979,187 disclose a conveyor system which gives an endless belt a 180.degree. twist at both the head and tail ends to keep the bottom or clean side of the belt against the return idlers. The 180.degree. twist is attained by supporting the belt at each end of the twist with horizontal terminal rolls. This twisting subjects the belt to catenary deflection, edge elongation from belt sag and formation of a helical pattern at the belt edge. The 180.degree. twist also does not subject the belt to gravity effects that may cause a loss of control of the belt during its travel.
The use of vertical rolls to twist an endless belt is disclosed in U.S. Pat. No. 3,637,090 to Murphy et al. The belt twisting is done to provide an improved belt storage system which permits rapid adjustment of the length of an active conveyor portion by removal of belt supporting sections mounted on skids from a storage portion to the active conveyor portion, and vice versa. With this adjustment, the length of the respective belt subsystems may be correspondingly adjusted as may be required in the field. The Murphy patent is adapted for use in the handling of bulk materials, e.g., mining operations or earth fill operations. Neither of these patents suggest a dual run conveyor system for baggage handling.